Collapsible dispensing tube having an anchored barrier member

ABSTRACT

A collapsible dispensing tube in which plastic fabricating materials other than conventional materials can be selected which are more suitable, since the pressure in the process is increased while the temperature is decreased. This manufacturing method utilizes a locking taper resulting in a better bond between the headpiece, barrier member, and the inner wall of the collapsible tube and substantially eliminating blowby of plastic material into said collapsible tube. The barrier member extends to and is tightly engaged with the adjacent inner wall of the collapsible tube and substantially eliminates bypass of gases around the barrier member. The method of manufacture permits the selection of the most suitable thermoplastic material for the intended use from a group of materials.

BACKGROUND OF THE INVENTION

The manufacture and fabrication of tubular articles of thermoplasticmaterials such as collapsible tubes are known and U.S. Pat. No.2,673,374 to Strahm discloses a method of manufacturing a tubularproduct in which a thin-walled plastic tube is formed and a shoulder andscrew-threaded cylindrical part affixed thereto by injection moldingthereby forming a tubular plastic article with a headpiece. Animprovement to the Strahm patent was U.S. Pat. No. 3,172,571 to Marchakin which a tubular body for a collapsible tube is formed of a laminatedconstruction having an intermediate layer that is impervious to thecontents of the tube while recognizing that some loss of moisture orproduct contents of the tube could take place through the plastic head.Marchak further stated that losses were held to a minimum because of therelatively thick plastic head. In U.S. Pat. No. 3,565,293 applicant hadconstructed a collapsible dispensing container with a deformable body oflow permeability and laminated construction, a thermoplastic headpiece,and an insert disc in the form of a barrier member that substantiallyeliminates product losses and which is spaced from the inner wall of thecollapsible tube. The headpiece is provided with an annular lipunderlying the peripheral edge of the barrier member. Another prior artconstruction is shown in U.S. Pat. No. 3,832,964 to Rockefeller in whichan inner head element is shown having a cylindrical skirt and anexternal annular flange. The disclosure in the Rockerfeller patentstates that the outer periphery of the flange has a diameter slightlyless than the diameter of the outer periphery of the skirt.

The present invention relates to a collapsible tube of the dispensingtype and a method of making the same wherein higher pressures are builtup thereby resulting in a reduced temperature and a faster fabricatingcycle.

It is an object of the present invention to provide a tube and headpiececonstruction for a collapsible tube in which a better bond is achieved.

Another object of the present invention is to provide a collapsible tubeconstruction which substantially eliminates blowby of the plasticmaterials utilized in the manufacture thereof.

It is an object of the present invention to have the ability to use lowdensity polyethylene for the material or other suitable materials of theheadpiece tube because of the ability to use higher pressures andthereby lower temperatures.

It is a further object of the present invention to provide a barriermember insert for the headpiece which extends to and tightly abuts theadjacent inner wall of the collapsible tube.

In order that the invention will be more clearly understood, it will nowbe disclosed in greater detail with reference to the accompanyingdrawings, in which:

FIG. 1 is a sectional view of a collapsible tube showing the headpieceand barrier member being formed by a die and mandrel in accordance withthe teaching of the method of the invention;

FIG. 2 is a sectional view of the completed collapsible tube combinationas fabricated in FIG. 1;

FIG. 3 is a partial elevational and a partial sectional view of anotherembodiment of the present invention;

FIG. 4 is another embodiment of the present invention illustrating amethod of manufacture of a collapsible tube having squared shoulders;

FIG. 5 is a fragmentary enlarged section of FIG. 3 showing the laminatedcollapsible tube structure and the back of the inside of a portion ofthe barrier member;

FIG. 6 is a partial sectional view of a further modification of thepresent invention;

FIG. 7 is a partial elevational view of the embodiment shown in FIG. 6,taken along the lines 7--7 of FIG. 6;

FIG. 8 is a partial sectional view, similar to FIG. 6, however showingan alternate embodiment of the present invention; and

FIG. 8a is a further partial sectional view of another embodiment of thepresent invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

A collapsible tube is shown in FIG. 1 of the type such as is used forthe dispensing of toothpaste and which is referred to generally by thereference numeral 8. The tubular body has a three-ply laminatedconstruction having inner and outer thermoplastic layers 12 and 16 andintermediate layer 14 constituting, for example, metal foil. Theheadpiece 18 for the tubular body comprises an easily moldablethermoplastic material such as low density polyethylene and includes athreaded neck portion 20 which is adaptable to receive a screw cap (notshown).

Referring to FIG. 1, the method of manufacturing the present collapsibletube is shown in which a thermoplastic collapsible laminated tube with afoil intermediate layer, and outer and inner layers of low densitypolyethylene is slid over a tapered mandrel 22 and the entire assemblypushed into a tapered die 24. Thread plates 26 move laterally to engagethe neck portion 20 to form threads thereon. Thus, the tube 8 initiallyfits loosely on the mandrel 22 and as the tapered die 24 moves down theaxis the top of the tube is bent about 10°, however, it is within thescope of the present invention to bend the top of tube 8 to any selectedangle between 5° to 20°. Furthermore, a space 28 is formed between themandrel 22 and the adjacent inner surface of the tube 8. A molding gate30 is located at the top of the assembly which permits the injectionmolding of plastic material therein forming a headpiece 18 locking inbarrier member 32. The barrier member 32 is provided with an angular,annular peripheral edge surface 34 that engages a correspondingly angledinner wall 36 of the tubular body 8. The locking taper formed by theaforesaid angled surfaces at A is clearly shown which permits thebuilding up of high pressures in the manufacturing process with thedesirable result of obtaining a faster process cycle as well as a betterbond between the headpiece, barrier insert and tubular body. Moreover,the locking taper configuration provides another clearly desirableresult in that blowby of the thermoplastic material is virtuallyeliminated upon the injection of the plastic material. In order toensure the reliable anchoring of the barrier member 32 to headpiece 18,the barrier member is provided with a lower bead 38 and upper beads 40.In this regard, it should be pointed out that the lower bead 38,although it assists in anchoring the barrier member, is not essential toachieve the desired result.

It should be apparent that there is a choice of desirable fabricatingmaterial since the temperature required for the process can be variedthereby permitting a faster cycle. For example, a lower heat may beemployed so that low density polyethylene can be used in themanufacturing process. It should also be evident that the present methodmay be used with or without the use of an insert or barrier member 32.It should be pointed out that known collapsible laminated dispensingtubes must use a higher melting high density thermoplastic materialsince the intermediate metallic layer, such as aluminum acts as a heatsink, and therefore more heat must be supplied in order to achieve abonding of the parts of the collapsible tube. On the other hand, thepresent invention allows more pressure to be applied, which achieves abetter heat transfer and consequently a better adhesion between theassembled parts of the collapsible dispensing tube, and also allows theuse of lower density polyethylene which softens at a lower temperature.

It is evident from a study of FIG. 1 of the drawings that the novelprocess resulting in the bending inwardly of the top of tube 8 at A,together with a corresponding bevelled surface 34 of the barrier member32, as well as the concomitant increase in pressure and the ability tolower the temperature, results in an exceptionally good bond of thetube, the thermoplastic headpiece and the barrier insert. Furthermore,the heat insulating characteristics of the present structure enhancesthe welding process. Moreover, the fact that the peripheral annular edgesurface 34 of the barrier insert engages an inner surface of the tube 10along its entire circumference prevents the flow of thermoplasticmaterial against the tooling during the injection molding steps. Thiscondition results in an insulating effect whereby the heat generatedwill be shunted to the laminated tube structure thereby permitting lowertemperatures.

Since the barrier member 32 has its free edge circumferentially engagingthe inner wall of tube 8, there is no cantilever effect on that memberas was the case in U.S. Pat. No. 3,565,293. Thus, in the prior artconstruction it was necessary to have a barrier member that was thickand stiff enough to withstand the forces generated by both hightemperatures and pressure. Consequently, in accordance with theteachings of the present invention, a relatively thin, flexible barriermember could be used in place of the conventional rigid insert presentlybeing employed. This relatively thin barrier member will function toprevent bypass of gases around its peripheral edge since it is either insubstantial engagement, or full engagement, with the adjacent inner wallof the tube 8.

Referring to FIGS. 3 and 5, an alternate embodiment of the presentinvention is shown having a barrier insert member referred to generallyby the numeral 42 that is castellated on its peripheral edge to formalternate projecting sections 46 and recessed sections 44. Theprojecting sections 46 abut the adjacent interior wall of thecollapsible tube 8 while the recessed sections 44, as seen in FIGS. 3and 5, receive a flow of thermoplastic material 48 from headpiece 18 toslots 47 that assists in anchoring the barrier insert member 42 to theheadpiece 18 as well as to tube 8. It will be noted that thethermoplastic material 48 is located between the barrier insert memberand an inner surface of the tube wall which is spaced therefrom atspaced locations about the circumference of the barrier insert member,but with substantial engagement by the peripheral surfaces of theprojecting portions of the barrier insert member along the adjacentinner wall of tube 8. A tapered die and a tapered mandrel, such as shownin FIG. 1 and described hereinbefore, is employed in the presentarrangement. FIG 4 shows the method of bending the top of tube 8 andforming a square shoulder tube 18a. The barrier insert member 42 is in acastellated form having spaced projections that engage a substantialportion of the inner wall of the tube 8, similar to the constructionshown in FIG. 3 and having thermoplastic material 48 that flows into thespaces between the projections. It will be observed from FIG. 4 that thetop edge 8a of the tube 8 is relatively straight and does not curlinwardly. This construction is possible since there is sufficient strongsqueeze of the laminates 12, 14 and 16 between the tapered die 24 andtapered mandrel 22 to allow high injection pressure without forcing thelaminates downwardly. Therefore, this arrangement permits theconical-shaped top of the tube to be squared off, hence presenting adifferent appearance of the tube, which conventionally has roundedshoulders, as seen in FIG. 3.

FIGS. 6 and 7 show a further embodiment of the present invention inwhich the barrier insert member 50 is provided with spaced holes 52 thatare cut into the member 50 so that the thermoplastic material 54, uponinjection molding, flows through the barrier holes 52 and functions toanchor the barrier insert member 50 to the headpiece 18 as well as thetube 8.

FIG. 8 is another alternative embodiment of the present invention and issimilar to the construction illustrated in FIG. 6, however the mandrel22 has a groove 23 which permits the inward flow of thermoplasticmaterial forming the headpiece 18 through the holes 52 to create anannular ring 55 below the barrier insert member 50. This arrangementfunctions to further strengthen the anchor of member 50 to the headpiece18 and collapsible tube 8.

FIG. 8a is a further embodiment of the present invention which issimilar to the construction shown in FIG. 8, however disclosing spacedgrooves 56 that permit the flow of thermoplastic material from theheadpiece 18 into an annular ring 58. The latter construction results ina reliable securement for the member 50.

A desirable result of the construction and method of manufacture, as setforth herein, is the production of a collapsible dispensing tube of thelaminated type in which a material may be selected from a choice offabricating materials especially for the specific use intended.

What is claimed:
 1. A collapsible container having a tubular body, athermoplastic headpiece molded to one end thereof, an impermeablebarrier member fixed to the inner wall surface of said headpiece andprovided with an extreme peripheral edge with space projecting partsengaging along the periphery of the adjacent inner wall surface of saidtubular body, and the areas therebetween having thermoplastic materialstherein, and means on said barrier member for securely anchoring saidbarrier member to the adjacent surface of said headpiece.
 2. Thecombination as claimed in claim 1 wherein at least one radial face of atleast one of said projecting part on the extreme peripheral edgediverges relative to the facing radial wall of the adjacent projectionwhereby the thermoplastic material that fills the space between theprojections mechanically wedge the barrier member against saidheadpiece.
 3. A collapsible container having a tubular body, athermoplastic headpiece molded to one end thereof, an impermeablebarrier member fixed to the inner wall surface of said headpiece andprovided with an extreme peripheral edge that engages the adjacent innerwall of said tubular body, and a plurality of spaced openings in thelower portion of said barrier member which perforate the latter, saidspaced openings having thermoplastic material therein whereby saidbarrier member, headpiece and tubular body are securely anchoredtogether.
 4. The combination as claimed in claim 3 wherein said barriermember includes a flared annular inner portion, a cylindricalintermediate portion and an outer portion which extends radially outwardfrom the cylindrical portion to form said extreme peripheral edge. 5.The combination as claimed in claim 4 wherein said spaced openingsperforate said cylindrical intermediate portion of said barrier member.6. The combination as claimed in claim 5 wherein said spaced openings inthe barrier member flare outward toward the surface of the barriermember not in contact with the headpiece.
 7. The combination as claimedin claim 3 wherein said lower portion of said barrier member isL-shaped.
 8. The combination of claim 3 further comprising an annularring constituted of the same thermoplastic material that is present insaid spaced openings and located below said barrier member, and integralwith said material in said openings.
 9. The combination of claim 3further comprising an annular ring of thermoplastic material under theextreme peripheral edge of said barrier member, and spaced channelsconnecting said spaced openings with said annular ring whereby thelatter is formed integrally with said headpiece.
 10. The combination asclaimed in claim 3 wherein said spaced openings in the barrier memberflare outward toward the surface of the barrier member not in contactwith the headpiece.
 11. The combination as claimed in claim 3 whereinsaid extreme peripheral edge and adjacent inner wall of said tubularbody each having a correspondingly small angle.
 12. The combination asclaimed in claim 11 wherein said angle is between 5° and 20°.